Free 25-hydroxyvitamin-D concentrations are lower in children with renal transplant compared with chronic kidney disease

Vitamin D levels in the pre- and post-COVID-19 pandemic periods in pediatric patients with chronic kidney disease

Introduction

Vitamin D (VD) deficiency is common in children with chronic kidney disease (CKD) because of multiple factors. During the coronavirus disease 2019 (COVID-19) pandemic, it increased because of medicine shortage and no enough medical service for patients with non-COVID-19 diseases.

Objective

To analyze the effects of the COVID-19 pandemic-related lockdown on the serum levels and status of 25-hydroxyvitamin D3 (25-[OH]D) in children with CKD.

Materials and methods

This retrospective study included patients (6-18 years old) who were diagnosed with CKD stage 2-5 and routinely measured for serum VD levels between May 2019 and December 2022. Serum 25-(OH)D levels were measured before, during, and after the pandemic (2019, 2020-2021, and 2022, respectively). The daily dose of cholecalciferol supplementation and the readjustment (if required) were recorded.

Results

This study included 171 patients (median age: 12 years). Before the pandemic, the median serum VD level was 25.0 ng/mL (19.3% VD deficiency). Then, VD supplementation was adjusted to 400-1,200 UI daily in 98.8% (n = 169) of patients. During the pandemic, the median VD level decreased to 22.5 ng/mL (43.3% VD deficiency). Hence, the supplementation was readjusted, and after the pandemic, the level was 28.7 ng/mL (18.7% VD deficiency), indicating a statistically significant increase in serum VD levels from the prepandemic period (p = 0.007).

Conclusion

Decreased serum VD levels and increased VD deficiency frequency were observed in patients with CKD during the COVID-19 but improved after readjustment of supplementation.

Body mass index is associated with hyperparathyroidism in pediatric kidney transplant recipients

BACKGROUND

Hyperparathyroidism persists in up to 50% of pediatric kidney transplant recipients. The aims of this study were to describe the evolution of parathyroid hormone (PTH) in the first year after transplantation and to identify factors associated with hyperparathyroidism.

METHODS

This retrospective study included children who underwent kidney transplantation at the University Hospitals of Ghent, Leuven, Rotterdam, or Amsterdam. Data from 149 patients were collected before and up to 12 months after transplantation. Severe hyperparathyroidism was defined as PTH 2-fold above the reference value. Factors associated with hyperparathyroidism and severe hyperparathyroidism were identified using multivariate logistic regression analysis.

RESULTS

Before transplantation, 97 out of 137 patients (71%) had hyperparathyroidism. The probability of hyperparathyroidism and severe hyperparathyroidism declined from 0.49 and 0.17 to 0.29 and 0.09 at 3 and 12 months after transplantation, respectively. BMI SDS (β: 0.509; p = 0.011; 95% CI: 1.122-2.468), eGFR (β: - 0.227; p = 0.030; 95% CI: 0.649-0.978), and pre-transplant hyperparathyroidism (β: 1.149; p = 0.039; 95% CI: 1.062-9.369) were associated with hyperparathyroidism 12 months after transplantation. Pre-transplant hyperparathyroidism (β: 2.115; p = 0.044; 95% CI: 1.055-65.084), defined as intact parathormone (iPTH) levels > 65 ng/l (6.9 pmol/l) or 1-84 PTH > 58 ng/l (6.2 pmol/l), was associated with severe hyperparathyroidism at 3 months. Only eGFR (β: - 0.488; p = 0.010; 95% CI: 0.425-0.888) was inversely associated with severe hyperparathyroidism at 9 months after transplantation.

CONCLUSIONS

Allograft function remains the main determinant of severe hyperparathyroidism after transplantation. Our findings emphasize the importance of BMI and pre-transplant PTH control.

Determining the optimal cholecalciferol dosing regimen in children with CKD: a randomized controlled trial

Background

The optimal treatment regimen for correcting 25-hydroxyvitamin D (25OHD) deficiency in children with chronic kidney disease (CKD) is not known. We compared cholecalciferol dosing regimens for achieving and maintaining 25OHD concentrations ≥30 ng/mL in children with CKD stages 2–4.

Methods

An open-label, multicentre randomized controlled trial randomized children with 25OHD concentrations <30 ng/mL in 1:1:1 to oral cholecalciferol 3000 IU daily, 25 000 IU weekly or 100 000 IU monthly for 3 months (maximum three intensive courses). In those with 25OHD ≥30 ng/mL, 1000 IU cholecalciferol daily (maintenance course) was given for up to 9 months. Primary outcome was achieving 25OHD ≥30 ng/mL at the end of intensive phase treatment.

Results

Ninety children were randomized to daily (n = 30), weekly (n = 29) or monthly (n = 31) treatment groups. At the end of intensive phase, 70/90 (77.8%) achieved 25OHD ≥30 ng/mL; 25OHD concentrations were comparable between groups (median 44.3, 39.4 and 39.3 ng/mL for daily, weekly and monthly groups, respectively; P = 0.24) with no difference between groups for time to achieve 25OHD ≥30 ng/mL (P = 0.28). There was no change in calcium, phosphorus and parathyroid hormone, but fibroblast growth factor 23 (P = 0.002) and klotho (P = 0.001) concentrations significantly increased and were comparable in all treatment groups. Irrespective of dosing regimen, children with glomerular disease had 25OHD concentrations lower than non-glomerular disease (25.8 versus 41.8 ng/mL; P = 0.007). One child had a 25OHD concentration of 134 ng/mL, and 5.5% had hypercalcemia without symptoms of toxicity.

Conclusion

Intensive treatment with oral cholecalciferol as daily, weekly or monthly regimens achieved similar 25OHD concentrations between treatment groups, without toxicity. Children with glomerular disease required higher doses of cholecalciferol compared with those with non-glomerular disease.

Association between 25(OH) vitamin D and graft survival in renal transplanted children

BACKGROUND

In children, vitamin D deficiency is common after renal transplantation. Besides promoting bone and muscle development, vitamin D has immunomodulatory effects, which could protect kidney allografts. The purpose of this study was to assess the association between vitamin D status and the occurrence of renal rejection.

METHODS

We studied a retrospective cohort of 123 children, who were transplanted at a single institution between September 2008 and April 2019. Patients did not receive vitamin D supplementation systematically. In addition, factors influencing vitamin D status were analyzed using univariate and multivariate analyses.

RESULTS

Median 25-hydroxy-vitamin D (25-OH-D) concentration was close to reference values at the time of transplantation (30 ng/mL (min-max 5-100)), but rapidly decreased within the first 3 months to 19 ng/mL (min-max 3-91) (P < .001). The overall acute rejection rate was 7%. The clinical rejection rate (5% vs 9%), subclinical rejection (12% vs 36%), and borderline changes (21% vs 28%) were not statistically different during the follow-up between the 3-month 25-OH-D < 20 ng/mL and 3-month 25-OH-D > 20 ng/mL groups. There was a correlation between the 25-OH-D levels and PTH concentration at 3 months (r = -.2491, P = .01), but no correlation between the 3-month 25-OH-D and the season of the year (F = 0.19, P = .90; F = 1.34, P = .27, respectively). Multivariate analyses revealed that age and mGFR at 3 months, were independent predictors of mGFR at 12 months.

CONCLUSION

Our data show that vitamin D deficiency can develop rapidly after transplantation; vitamin D levels at 3 months are not associated with lower mGFR or a higher rejection rate at 1 year in children as opposed to adult recipients.